The evidence I have produced, to explain how I formed an opinion on a subject I have no knowledge of, is not "random."

It is the hard evidence of the convictions and of Wilmer's case files, and the observations of eminent and responsible people in public life.

Lox and Jim refuse to give that evidence any recognition.
They ignore it simply because it challenges their dogma.
It just can't be true, and only a racist would think so.

If you only accept that the evidence is in the very least suggestive that an issue exists, it is perfectly legitimate to ask why.
But not to Lox and Jim.
That also challenges their dogma, so it is racist.